Paper Technology Journal 17 - Voith

ASN (Average size number)
Dryness after 2nd press
55
50
45
40
59
58
57
56
55
54
53
52
3.3 dtex 5 dtex 11 dtex 17 dtex
Very fine
batt
Medium
batt
PrintFlex P
5
Fabric permeability, cfm
70
60
50
40
30
20
10
0
Very fine
batt
Fabrics
Fig. 1: ASN for press fabrics with different
surface properties.
Fig. 2: ASN index comparison for press fabrics
having different surface properties.
New
After running
Fig. 3: FIN index comparison for press fabrics
having different surface properties.
New
After running
1 60
2 55
3
4
PrintFlex P, forms stage 2 of Voith
Fabrics ‘4-stage platform’ for pressing.
PrintFlex P is composed of a surface
made of fine batt fiber, layered with engineered
resin components. It provides an
extremely high degree of pressing uniformity,
with excellent wear resistance.
Figs. 2 and 3 show the comparison of
results between a ‘standard’ press fabric,
with a fine 6.7 dtex surface, and Print-
Flex P.
It can be observed that the PrintFlex P
has an ASN number almost 10 % lower
than the ‘standard’ fabric. The FIN index,
shows over 40 % improvement for Print-
Flex P over the ‘standard’ fabric surface.
ASN (Average size number)
50
45
40
35
30
PrintFlex P 6.7 dtex
surface
Figs. 2 and 3 show the comparison of
ASN and FIN between new and used fabric.
Analysis of the fabric permeabilities
showed that the PrintFlex P retained over
33 % of more of its original permeability
after use, compared to the ‘standard’ design.
It is important to also note that despite
the application of the engineered
resin components, the PrintFlex P design
was manufactured to the same level of
starting permeability as the ‘standard’
design.
Mechanical abrasion tests have also
demonstrated the high wear resistant
properties of PrintFlex P. Again, compared
to the ‘standard’ design, PrintFlex P
Medium
batt
PrintFlex P
Fig. 4: After press dryness results for different
batt structures – VPM4.
Fig. 5: Permeability of press fabrics
New – VPM4.
FIN
60
50
40
30
20
10
0
61
gave almost 10 % less weight loss. The
benefits of this can be seen from the case
study shown in Fig. 9.
Dryness/Rewet
PrintFlex P 6.7 dtex
surface
Initial evaluations of PrintFlex P were carried
out on the VPM4 pilot machine in
Heidenheim, Germany, to investigate the
influence of fabric surface properties on
sheet dryness and sheet quality. An SC
magazine furnish was used for the tests.
Three different sets of press fabrics having
different surface properties were tested:
a ‘fine’ (3.3 dtex), ‘coarse’ (17 dtex)
and PrintFlex P.
Dryness values were taken after the second
press (Fig. 4). PrintFlex P provided
the highest dryness values of over 55 %.
Another important aspect to consider is
the permeability of the press fabrics. The
PrintFlex P had a permeability of 58 cfm,
the ‘medium batt’ fabric 63 cfm, whilst
the ‘very fine’ fabric only 18 cfm (Fig. 5).
17/04